Rock drill bit



R. L. KIRKER ROCK DRILL BIT Filed March 28, 1962 April 14, 1964 Ila IN VEN TOR. ROBERT LOPEZ KIRKER a ATTORNEYS United States Patent 3,128,835 RGCK DRILL BIT Robert L. Kirker, Central, N. Mex., assignor to Kenneeott Copper Corporation, New York, N .Y., a corporation of New York Filed Mar. 28, 1962, Ser. No. 183,126 3 Claims. (Cl. 175-401) This invention relates to rock drill bits for percussion drilling and is concerned with improving an existing type of multi-wing rock bit.

Percussion drilling is employed extensively in mining and construction work, particularly for making blasting holes. It involves the use of a bit at one end of a long rod, which is subjected to combined percussive and rotary action by a drilling machine. The rotary action is primarily for the purpose of constantly changing the bite of the bit. It has very little if anything to do with the cutting action. It is customary for the bit to be made separable from the drill rod, so as to be easily replaceable, and to include silicon carbide inserts in the cutting face as cutting or drilling elements.

The cutting face of the bit is ordinarily defined by several cutting wings and is of greater diameter than the drill rod. For this reason considerable difficulty is often encountered in extracting the drill rod and bit following completion of the hole, particularly in those instances where the rock formation drilled is of broken character. Rock pieces tend to fall into the hole behind the bit and wedge tightly into place under the back pressure of drill extraction.

This difficulty has been widely recognized, and attempts have been made heretofore to remedy the situation. These have been concerned primarily with providing reaming flanges on a portion of the drill assembly located backwardly of the bit, see for example U.S. Patent Numbers Re. 16,061; 2,579,720; 2,739,791; and 2,958,513.

While, as is noted in U.S. Patent No. 2,739,791, attempts have been made to incorporate reaming flanges on the bit itself, such attempts have not been satisfactory because of excessive drill load and consequent excessive power requirements. Locating reaming flanges on the drill rod has not been satisfactory, because a given drill rod is ordinarily used with any one of a number of different sizes of bits. A drill rod with reaming flanges requires a bit of a given size and makes it impractical to use the same rod for diiferent sized bits.

A principal object in the making of the present invention was to provide a bit of the type concerned which would overcome the aforementioned difficulties, without unduly increasing drill load or power requirements.

A feature of the invention in the accomplishment of this object is the provision, in a so-called cutaway bit, of a set of two diametrically opposite cutter ribs extending backwardly of the cutting face and upwardly of the shank as continuations of respective diametrically opposite cutting wings of the bit. Such cutter ribs have longitudinal cutting edges, which are similarly directed opposite to the normal direction of rotation of the bit during drilling. The ribs taper backwardly from their longitudinal cutting faces to mergence with the shank, thereby providing strong backing for the cutting edges. They also preferably taper axially of the bit, and are canted along their lengths in the direction of normal bit rotation. In this way provision is made for chewing up debris in the hole above the bit during extraction of bit and drill rod following completion of a hole, without causing excessive drill load and adding unduly to power requirements.

There is shown in the accompanying drawing a specific embodiment representing what is presently regarded as the best mode of carrying out the invention. From the detailed description of this, other more specific objects and features will become apparent;

In the drawing:

FIG. 1 is a view showing in side elevation a cutaway rock drill bit conforming to the invention, one of the cutter ribs being directly confronted;

FIG. 2, a top plan; and

FIG. 3, a bottom plan.

Referring to the drawing:

The illustrated cutaway bit has four cutter wings indicated 10, respectively, terminating, as is customary in this style of bit, in a shank 11 of lesser diameter than the cutting face 12 defined by a circle joining the outer extremities of the wings. As is shown, the shank 11 tapers toward the cutting face in a general conical formation 11a, which facilitates forcing of the cuttings peripherally of the shank by wash fluid injected in customary manner through the interior of the drill rod (not shown) and out through passage 13 of the bit. The lower end of the drill rod screws or otherwise fits into recess 14 of the bit in removably attaching bit to rod.

Properly shaped inserts 15 of silicon carbide or other special cutting material are provided in the respective wings 10 in customary manner.

In accordance with the invention, a set of diametrically Opposite cutter ribs 16 are provided longitudinally of the bit. These extend backwardly from corresponding cutting wings 10 and along the length of shank 11. They are advantageously tapered axially of the bit, as indicated in FIG. 2, and are also preferably canted in the direction of normal bit rotation, as indicated in FIG. 1. They have cutting faces 16a, respectively, and cutting edges 16b, respectively, similarly directed opposite to the direction of normal rotation of the bit.

Tllus, when the drill rod and bit are being rotated backwardly during withdrawal from the drill hole, the cutting ribs 16 serve to chew up any debris which might otherwise prevent or hinder the withdrawal operation.

The ribs 16 taper backwardly from their cutting faces 16a along gently sweeping curves 16c, FIG. 2, to provide substantial backing for the cutting faces and edges, without hampering the drilling operation when the bit is rotating in the normal direction during the drilling operation.

From the drawing, it will be seen that the invention provides a rock drill bit of multi-wing, cutaway type adapted for attachment to one end of an elongate drill rod (not shown). The bit comprises a shank portion 11 of substantially uniform diameter, having a plurality of V-shaped cutter Wings 10 integral therewith at one of its ends and drill rod attachment means in the form of recess 14 at its other end. The wings 10 extend outwardly beyond the periphery of the shank portion to define a cutting face 12 for the bit. Such cutting face, therefore, has a diameter greater than the diameter of the shank portion, and at least two of the cutter wings 10 are diametrically opposite each other. Extending backwardly from these two cutter wings, integrally therewith and with the shank portion 11 of the bit, is a set of two diametrically opposite cutter ribs 16. These are longitudinally rectilinear and extend along the length of the shank portion 10 and are tapered inwardly toward the shank portion in their backward extension from the respective wings. They have oppositely directed, lateral cutting faces 16a, which intersect corresponding lateral faces of the respective wings and are canted inwardly of such wings and are tapered inwardly of the bit commencing above and in spaced relation to the cutting face 12 of the bit, as shown in FIG. 1. One end of shank portion 11 is tapered, as at 11a, toward the cutting face 12 of the bit. Except for the two cutter ribs 16, shank portion 11 of the bit is substantially free of lateral encumbrances.

Whereas there is here illustrated and described a certain preferred construction which I presently regard as the best, mode of carrying out my invention, it should be understood that various changes may be made without departing from the inventive concepts particularly pointed out and claimed herebelow.

I claim:

1. A rock drill bit of multi-wing, cutaway type adapted for attachment to one end of an elongate drill rod, said bit comprising a shank portion of substantially uniform diameter; a plurality of Vshaped cutter wings integral with the shank portion at one end thereof and extending outwardly beyondthe periphery of the shank portion to define a cutting face for the bit having a diameter greater than the diameter of the shank portion, at least two of said wings being diametrically opposite each other; means at the opposite end of the shank portion for attaching the bit to a drill rod; and a set of two diametrically opposite, longitudinally rectilinear, cutter ribs extending backwardly from said two diametrically opposite wings integrally therewith and along the length of and integral-with the shank portion, said. cutter ribs having oppositely directed,

lateral cutting faces which intersect corresponding lateral faces of their respective wings above and in spaced rela- .4 Wardly of the bit from the intersections of their cutting faces with said lateral faces of the wings, respectively, and said one end of the shank portion being tapered toward said cutting face of the bit,,the shank portion being substantially free of lateral encumbrances except for said cutter ribs.

2. The rock drill bit of claim 1, wherein the tapered one end of the shank merges with the cutter wings short of the cutting face of the bit.

3. The rock drill bit of claim 1, wherein there are cutting inserts in the vertex portions of the cutter wings, respectively, at the cutting face of the bit; wherein passage means for a drilling fluid is provided axially of said bit and opening centrally of said cutting face; and wherein said cutting inserts terminate short of the center of said cutting face.

References Cited in the file of this patent UNITED STATES PATENTS 1,169,369 Wakfer Jan. 25, 1916 2,519,861 Turner Aug. 22, 1950 2,602,639 Green July 8, 1952 2,633,335 Hart Mar. 31, 1953 2,971,594 Spencer Feb. 14, 1961 3,043,385 Boyle July 10, 1962 

1. A ROCK DRILL BIT OF MULTI-WING, CUTAWAY TYPE ADAPTED FOR ATTACHMENT TO ONE END OF AN ELONGATE DRILL ROD, SAID BIT COMPRISING A SHANK PORTION OF SUBSTANTIALLY UNIFORM DIAMETER; A PLURALITY OF V-SHAPED CUTTER WINGS INTEGRAL WITH THE SHANK PORTION AT ONE END THEREOF AND EXTENDING OUTWARDLY BEYOND THE PERIPHERY OF THE SHANK PORTION TO DEFINE A CUTTING FACE FOR THE BIT HAVING A DIAMETER GREATER THAN THE DIAMETER OF THE SHANK PORTION, AT LEAST TWO OF SAID WINGS BEING DIAMETRICALLY OPPOSITE EACH OTHER; MEANS AT THE OPPOSITE END OF THE SHANK PORTION FOR ATTACHING THE BIT TO A DRILL ROD; AND A SET OF TWO DIAMETRICALLY OPPOSITE, LONGITUDINALLY RECTILINEAR, CUTTER RIBS EXTENDING BACKWARDLY FROM SAID TWO DIAMETRICALLY OPPOSITE WINGS INTEGRALLY THEREWITH AND ALONG THE LENGTH OF AND INTEGRAL WITH THE SHANK PORTION, SAID CUTTER RIBS HAVING OPPOSITELY DIRECTED, LATERAL CUTTING FACES WHICH INTERSECT CORRESPONDING LATERAL FACES OF THEIR RESPECTIVE WINGS ABOVE AND IN SPACED RELATION TO SAID CUTTING FACE OF THE BIT, AND SAID CUTTER RIBS BEING TAPERED INWARDLY TOWARD THE SHANK PORTION IN THEIR BACKWARD EXTENSION FROM THEIR RESPECTIVE WINGS AND CANTED INWARDLY OF SAID RESPECTIVE WINGS AND TAPERED INWARDLY OF THE BIT FROM THE INTERSECTIONS OF THEIR CUTTING FACES WITH SAID LATERAL FACES OF THE WINGS, RESPECTIVELY, AND SAID ONE END OF THE SHANK PORTION BEING TAPERED TOWARD SAID CUTTING FACE OF THE BIT, THE SHANK PORTION BEING SUBSTANTIALLY FREE OF LATERAL ENCUMBRANCES EXCEPT FOR SAID CUTTER RIBS. 